Golf Mk II heater not working

[Paul L]

I'm Paul and a new member. My wife has a J reg (1992) Golf Driver. The heater motor works fine but it won't blow hot. I've replaced the thermostat and all the pipes get hot but it blows cool air and she (the wife) can't get warm. Can anyone please suggest what the problem is and how I can fix it. Cheers and happy new year. Paul L

[Crasher]

In the rubber hoses to the bulkhead for the heater matrix from the head and the water transfer pipe (the metal pipe that runs around to the front of the engine), you will find two valves, one metal and one plastic. These were fitted as part of a recall to prevent the heater matrix exploding. Unfortunately the valves get a little enthusiastic about cutting off the flow of water to the matrix and cause the problem you are experiencing. These valves are available from VW dealers as kit under the part number 191 819 911 A for £32.28. You MUST NOT remove and bypass these valves unless the heater unit is removed and the matrix is replaced by a brand new ONLY genuine VW Golf 3 revised spec heater matrix, part number 1H2 819 031 B which costs £115.13. If the valves are bypassed, you run a significant risk of boiling hot water being sprayed all over your wife’s legs and it has even been known to spray out of the face level heater vents. The other possibility is a blocked heater matrix and the design of the matrix makes it impossible top flush it out.